"We note that prior to the broadcast RadioLive sought guidance from the Electoral Commission and endeavored to comply with the advice given."

Police said inquiries were ongoing into 23 other referrals from the Electoral Commission on election advertising or election programmes and 62 dual voter complaints.

Labour's deputy leader Grant Robertson said while his party acknowledged the police decision not to lay charges, it continued to agree with the Electoral Commission that the programme broke electoral law.

Regardless of the decision by police today, the fact remains that John Key got free publicity, potentially worth tens of thousands of dollars, when he was gifted the right to host a radio show during the run-up to the election.

The police note that RadioLive made an effort to comply with the Electoral Commission's advice to take extreme care. But that same Electoral Commission found that the programme breached electoral law.

John Key could not resist the opportunity to promote himself and his friendships with celebrities before the election. It was a political stunt and he should have taken responsibility for that, Mr Robertson said in a statement.